Defrosting of refrigeration systems



March 31, 1964 E. J. KOCHER DEF'ROSTING OF REFRIGERATION SYSTEMS FiledJune 18, 1962 INVENTOR. C520? %0cr BY M M 8 RLZZM United States Patent3,126,715 DEFROSTING 0F REFRIGERATION SYSTEMS Erich J. Kocher,Milwaukee, Wis., assignor to Vilter Manufacturing Corporation,Milwaukee, Wis., a corporation of Wisconsin Filed June 18, 1962, Ser.No. 203,338 Claims. (Cl. 62-151) The present invention relates generallyto improve ments in the art of refrigeration, and relates moreparticularly to the provision of an improved hot gas defrosting systemwhich embodies novel automatically operable valves.

A primary object of the invention is to provide an improved defrostingarrangement ior refrigeration systems which is extremely simple yethighly efiicient in operation, and wherein hot gas from the dischargeside of the compressor is used for defrosting the refrigeration coils.

Various arrangements have heretofore been proposed for defrosting thecooling coils or evaporators in refrigeration systems by means of hotgas conducted to the coils from the high pressure side of thecompressor, and such prior systems have likewise embodied diverse typesof flow control valves for regulating and selectively controlling theflow of refrigerant and/ or hot gas to the evaporator. However, asexemplified in United States Patents No. 2,596,036, dated May 6, 1952 toF. M. MacDougall, No. 2,632,303, dated March 24, 1953 to V. W. Smith,No. 2,762,206, dated September 11, 1956 to C. M. Ashley, and No.2,823,691, dated February 18, 1958 to G. N. Chatham et al., the valvingmeans heretofore proposed in these hot gas defrosting systems allrequire mechanical connections or the like between the valve and theactuating element or elements, thus rendering such systems undesirablycomplicated and costly.

It is therefore a further object of the present invention to provide animproved hot gas defrosting means for refrigeration systems whichobviates the objections and disadvantages attendant prior systems anddevices.

Another important object of this invention is to provide an improveddefrosting system in which the hot gas from the high pressure side ofthe compressor is used for directly actuating the valves controllingflow through the cooling coils.

Another object of the invention is to provide a defrosting systemembodying a flow and valving arrange ment wherein the velocity of thehot gas itself actuates the valves controlling flow through theevaporator, thereby effectively eliminating the need for separate valveactuators.

Still another object of the present invention is to provide improvedvalve assemblages for the evaporator coils in a refrigeration systemwhich are completely self-contained and controlled entirely by theaction of hot gas used for defrosting and conducted thereto atcontrolled intervals from the high pressure side of the compressor.

These and other more specific objects of the invention will be apparentfrom the following detailed description.

A clear conception of the features constituting the present improvementand of the construction and operation of a typical system embodying theinvention may be had by referring to the drawing accompanying andforming a part of this specification wherein like reference charactersdesignate the same or similar parts in the several views.

FIG. 1 is a more-or-less diagrammatic view illustrating a typicalrefrigeration system provided with the improved defrost-ing means forone set of coils and showing the accumulator in section;

FIG. 2 is an enlarged fragmentary vertical section through the hot gascontrolled check valve at the upper or 2 discharge end of the evaporatoror cooling coil and showing the valve in normally open position;

FIG. 3 is a likewise enlarged fragmentary vertical section through thelower inlet end of the cooling coil housing the refrigerant inlet valveand likewise showing the same in normally open position;

FIG. 4 is a section similar to FIG. 2 but showing the upper valve inclosed position for the defrosting operation; and

FIG. 5 is a sectional view corresponding to FIG. 3 but with the lowervalve in its closed defrosting position.

While the invention has been shown and described herein as beingembodied in a simple refrigerating system having but a single evaporatoror cooling coil in which the defrosting cycle is controlled by asolenoid valve operated by a timer or the like, it is not intended tothereby unnecessarily limit the scope or utility of the improvementssince they may be employed with equal effectiveness in a systemembodying a multiplicity of cooling coils adapted for defrosting in anydesired order and timed relationship. It is also contemplated thatcertain specific descriptive terminology used herein shall be given thebroadest possible interpretation consistent with the disclosure.

Referring to the drawing, the refrigeration system shown thereincomprises, in general, .a compressor .16 for distributing hot gas undercompression through a conduit 11 past a check valve 12. to a condenser13 from which the condensed high pressure liquid refrigerant isdelivered to a receiver 15 through a connection t4, the liquidrefrigerant being supplied from the receiver 15 to an accumulator 17 viaa conduit 16 under the control of a float valve 18. Connected with thelower interior of the accumulator 17 as by means of a conduit 2b is anevaporator or cooling coil 21, the upper end of which is connected withthe upper interior of the accumulator above the float valve is by aconduit 22, it being understood that the system may include any desirednumber of cooling coils 21 connected with the accumulator 17 in likefashion.

In normal operation during cooling, the compressor it) withdraws thevapor or refrigerant gas from the upper interior vapor space of theaccumulator 17 via conduit 23. The relatively hot compressed gas is thenconducted through conduit 11 under control of the check valve 12 to thecondenser 13 wherein it is condensed. From the condenser, the highpressure liquid refrigerant is delivered by way of the connection 14 tothe receiver 15 from which it is conducted via conduit 16 as required,under the control of the float valve 18, to the accumulator 17. Theliquid refrigerant is then delivered from the lower interior of theaccumulator 1'7 through conduit 20 to the evaporator coil 21 to performits cooling function as it boils within the coil, the vapor beingdischarged through the conduit 22 to the upper interior of theaccumulator 1'7 to complete the cycle.

To periodically remove ice formations from the evaporator tube orcooling coil 21, the present invention uses hot gas discharged from thecompressor 16 under pressure, and while this concept by itself is old, apair of novel and unique check valves are employed in the present systemwhich are automatically operable in response to the velocity of the hotgas conducted thereto during the desired periods of the defrostingoperations. These valves are located at the upperor discharge end of thecooling coil 21 and at the lower inlet end thereof and are designatedgenerally by the numerals 25, 26 respectively.

Referring particularly to FIGS. 2 and 4 of the drawing, the valve 25comprises a generally tubular body 27 secured in a convenient mannerbetween the coil 21 and conduit 22 and housing a valve disk 23 guidedfor recip- .3 rocable movement as by means of a plurality of annularlyspaced positioning and guide pins 29, the valve disk 28 beingresiliently urged toward open position, as shown in FIG. 2, as by meansof a relatively heavy spring 3t] held against displacement by a splitring 31 or the like.

As shown in FIGS. 3 and 5, the valve 26 comprises a similar tubular body33 likewise secured in a convenient manner between the lower end of thecoil 21 and the conduit 26, the valve body 32 also housing a valve disk33 retained within and guided for movement by a cage 34 having anapertured stop plate and a plurality of annularly spaced guide legs. Inthe case of the valve 26, the valve disk 33 is resiliently urged towardits open position and into seated contact with the apertured plate ofthe cage 34 as in FIG. 3 by means of a relatively light spring 35 merelysufiicient to augment the flow of refrigerant from the accumulator 1'7and conduit 28 in holding the valve disk 33 in its open position, theValve disk 33 being provided with a bleed aperture 36 axially alinedwith the aperture 39 in the stop plate 38 of the cage 34 for reasonswhich will hereafter become apparent. The spring 35 employed in thevalve assemblage 26 may likewise be effectively seated on and retainedagainst axial displacement by means of a split ring 37 or the like.

During the cooling or refrigerating cycle heretofore described, thevalve disk 23 of the valve 25 is normally effectively maintainedunseated and open by the action of the relatively heavy spring 36permitting the flow of refrigerant to continue from the coil 21 to theconduit 22 as shown by the arrows in FIG. 2. At the same time, the valvedisk 33 of the valve 26 is caused to remain open by the combined actionof the lighter spring 35 and the flow pressure of the liquid refrigerantconducted to the coil 21 by way of the conduit Zn from the bottom of theaccumulator, the fiow of liquid refrigerant during such cooling cyclebeing illustrated by means of arrows in FIG. 3.

To close the valves 25, 26 and cause hot gas to be conducted to thecooling coil 21 for the defrosting operation, a conduit 4a) is providedbetween the discharge or high pressure side of the compressor It) andthe lower side of the disk 28 of the valve 25, the conduit 40terminating immediately below the valve disk 28 so as to act as a stopfor the valve disk and prevent displacement thereof as a result of theaction of the spring 3d. Interposed in the conduit 43 is a suitable flowcontrol valve shown in the drawing as being in the form of a solenoidvalve 41, and this valve may be actuated as desired by a timer or othersuitable means to open the conduit as at desired time intervals andinitiate the defrosting operation as follows. When the valve 41 isopened to admit hot gas through the line 40 from the high pressure sideof the compressor to the lower face of the valve link 3, the velocity ofthe hot gas acts on the valve disk 28 and causes the same to closeagainst the action of the spring 38!. Upon closing of the valve 25 bythe seating of the valve disk 28 as shown in FIG. 4, the pressure in theevaporating or cooling coil 21 builds up sufficiently to overcome theforce of the relatively light spring 35 cooperating with the flow ofliquid refrigerant to hold the valve disk 33 in its open position, andthe valve disk 33 will consequently seat and close the valve 26 as shownin FIG. 5. The hot gas thereby replaces the refrigerant in the coil 21,and as long as the valves 25, 26 remain closed as shown in FIGS. 4 and5, the hot gas defrosting operation will continue and the cooling cyclewill again be commenced upon closing of the valve 41 to shut off flow ofhot gas to the valve 25. To permit escape of entrapped refrigerant fromthe evaporator and allow operation of the valve 33 While preventingover-pressurization within the coil 21 during the defrosta ingoperation, aperture 36 in the valve disk 33 is provided for bleed-off.

The improved hot gas defrosting system thus eliminates need formechanical connections and actuators for the valves 25, 26, and thesevalves may be of extremely simple and economical construction. Thevalves 25, 26 are also capable of ready installation, and the defrostingcycles may be conveniently automatically timed as desired. While thevalve disks 28, 33 have been illustrated as being generally ofdish-shape, they have been so designed primarily for convenience inretaining the respective springs in seated position thereagainst. Also,as already heretofore indicated, a plurality of evaporator or coolingcoils may likewise be effectively defrosted at timed intervals in amanner similar to that described herein.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. A refrigerating system comprising, a compressor, a condenser, conduitmeans for conducting refrigerant gas under compression from saidcompressor to said condenser, an evaporator having an inlet end and anoutlet end provided with a coaxial tubular valve body, conduit means fordelivering liquid refrigerant from said condenser to the inlet end ofsaid evaporator, an expansion device in said conduit, other conduitmeans from said tubular valve body to said compressor, a reciprocabledisk-shaped valve housed within said valve body and peripherally spacedtherefrom for controlling flow of refrigerant through said evaporator,resilient means acting on one face of said valve in opposition to thenormal flow of refrigerant through said evaporator for normallymaintaining said valve in open condition for the refrigerating cycle,separate conduit means extending from the discharge side of saidcompressor into said valve body coaxially thereof and terminatnigtherein immediately adjacent the opposite face of said valve to providea seat therefor when said valve is in open condition, and flow controlmeans in said separate conduit for periodically delivering gas undercompression therethrough and directly against said valve in oppositionto said resilient means to close the same in response to the velocity ofsaid gas delivered thereto and thereby interrupt normal flow ofrefrigerant through said evaporator to cause defrosting thereof.

2. A refrigerating system according to claim 1, wherein guide means areprovided in the valve body for guiding the valve in its reciprocablemovement to maintain the same peripherally spaced from the side Wall ofsaid body.

3. A refrigerating system according to claim 1, wherein the inlet end ofthe evaporator is also provided with a coaxial tubular valve bodyhousing a disk-shaped valve peripherally spaced from the body withinwhich it is housed.

4. A refrigerating system according to claim 3, wherein resilient meansare also provided acting on one face of the inlet valve in the directionof normal flow of refrigerant through the evaporator for normallymaintaining said inlet valve in open condition.

5. A refrigerating system according to claim 4, wherein the resilientmeans acting on the outlet valve is a relatively heavy spring and theresilient means acting on the inlet valve is a relatively light spring.

References Cited in the file of this patent UNITED STATES PATENTS2,451,385 Groat Oct. 12, 1948

1. A REFRIGERATING SYSTEM COMPRISING, A COMPRESSOR, A CONDENSER, CONDUITMEANS FOR CONDUCTING REFRIGERANT GAS UNDER COMPRESSION FROM SAIDCOMPRESSOR TO SAID CONDENSER, AN EVAPORATOR HAVING AN INLET END AND ANOUTLET END PROVIDED WITH A COAXIAL TUBULAR VALVE BODY, CONDUIT MEANS FORDELIVERING LIQUID REFRIGERANT FROM SAID CONDENSER TO THE INLET END OFSAID EVAPORATOR, AN EXPANSION DEVICE IN SAID CONDUIT, OTHER CONDUITMEANS FROM SAID TUBULAR VALVE BODY TO SAID COMPRESSOR, A RECIPROCABLEDISK-SHAPED VALVE HOUSED WITHIN SAID VALVE BODY AND PERIPHERALLY SPACEDTHEREFROM FOR CONTROLLING FLOW OF REFRIGERANT THROUGH SAID EVAPORATOR,RESILIENT MEANS ACTING ON ONE FACE OF SAID VALVE IN OPPOSITION TO THENORMAL FLOW OF REFRIGERANT THROUGH SAID EVAPORATOR FOR NORMALLYMAINTAINING SAID VALVE IN OPEN CONDITION FOR THE RE-